Electromagnetic holding mechanism



T. H. voGELsANG 3,526,863 ELECTROMAGNETIG HOLDING MECHANISM Filed 0G11. 50, 1967 loa` AFIGS v#VVE/vraie' loMAs H, Vacas/WG Sept. l, 1970 l United States Patent Oiiice 3,526,863 Patented Sept. l, 1970 U.S. Cl. 335--186 15 Claims ABSTRACT OF THE DISCLOSURE An electromagnetic holding mechanism for use with an actuating device and a switching device to hold the switching device in its actuated position after being actuated by the actuating device. The holding mechanism includes a coil enclosed with a magnetic assembly, which assembly is supported within a housing formed of a pair of identical insulating housing halves. A magnetic plunger is received within the bore of the coil and operatively engages the actuating device at one end and is provided with an extension at the other end for operatively engaging the switching device. Actuation of the actuating device actuates the magnetic plunger, the switching device, and also closes a pair of switch contacts through which the coil is energized to maintain the magnetic plunger and the switching device in their actuated positions irrespective of the position of the actuating device.

BACKGROUND OF THE INIVENTION This invention relates to electromagnetically actuated switches and more particularly to the housing and magnetic structure of such switches.

The assignee of this application manufactures and sells separate actuating devices and switching devices, each of which is manufactured and sold in many Varieties. v'The housings of these switching and actuating devices are readily joined to each other to form push button actuated switches having various combinations of normally open and normally closed contacts and either momentary or alternate action. It has now been found desirable to provide an electromagnetic mechanism for use with the switching and actuating devices which will electromagnetically maintain the switching devices in the actuated position after they have been atcuated -by the actuating devices, irrespective of the subsequent position of the actu ating device, until the electromagnetic mechanism is deenergized. The combined magnetic and manual switches provided in the past have been characterized by .a complex unitary structure, wherein exibility of operation and contact arrangement was not easily provided, and wherein tthe structure was quite diicult to assemble.

OBJECTS OF THE INVENTION It is therefore a primary object of this invention to provide a novel and improved electromagnetic holding mechanism which is particularly adapted for optional use with separable switching devices and actuating devices to hold the electrical switching device in an actuated position to which it has been Amoved by the application of an actuating force to the actuating device.

It is another object of the invention to provide a novel and improved electromagnetic holding mechanism which incorporates a minimum number of inexpensive parts which are readily assembled with minimal effort and skill.

SUMMARY OF THE INVENTION of the electromagnetic holding mechanism a coil and a magnetic assembly which includes a ixed magnetic portion and a movable magnetic portion, are assembled within a housing. The xed magnetic portion surrounds the coil and the movable magnetic portion is in the form of a magnetic cylinder received in the bore of the coil to provide a magnetic path encircling the coil. The xed magnetic portion is secured between two identical insulating housing halves which are secured at one end to the switch housing and at the opposite end to the actuator housing to form a composite housing. The movable magnetic portion is provided with a shaft extension at one end which is seprate form and which engages an operating member in the switching device. Ther other end of the magnetic cylinder is separate from and engages an actuator in the actuating device so as to transmit actuating movement of the actuator in the actuating device to the operating member in the switching device.

The housing halves of the holding mechanism support iixed contacts which are engageable with movable contacts carried by the actuator to form a control switch through which the coil is energized. Energization of the coil is effective to maintain the movable magnetic portion in its actuated position, thereby maintaining the operating member in its actuated position irrespective of the removal of the actuating force from the actuator. The movable magnetic portion and the operating member are only released from their actuated positions by subsequent deenergization of the coil by means independent of the control switch contacts.

Other objects and further details of that which is believed to be novel in the invention will be clear from the following description and claims taken with the accompanying drawing wherein:

BRIEF DESCRIPTION OF THE DRAWING and improved electromagnetic holding mechanism contemplated by this invention;

FIG. 2 is an exploded view of the electromagnetic holding mechanism of the assembly shown in FIG. l;

FIG. 3 is an enlarged side view of the composite assembly shown in FIG. 1, with some portions removed and other portions broken away, with the actuating device, switching device, and the electromagnetic holding mechanism in their unactuated positions;

FIG. 4 is a side view of portions of the electromagnetic holding mechanism and of the switching device shown in FIG. 3, in their actuated positions;

FIG. 5 is a sectional View taken substantially along line 5-5 in FIG. 4; and

FIG. f6 is a circuit diagram for the electromagnetic holding mechanism.

DESCRIPTION OF A PREFERRED EMBODIMENT -Referring to FIG. 1, one embodiment of the electromagnetic holding mechanism as utilized with a push button actuating device and a switching device will be described. The push button actuating device includes a housing assembly 10 and an illuminable push button The housing assembly is adapted to be secured in a rectangular aperture in a panel (not shown) by the engagement of a flange 26 provided around the open end of the housing 14 and arms 28 of a pair of spring members or retaining clips 30 (not one shown in FIG. 1) with opposite sides of the panel (not shown). The retaining clips 30 are secured to the side walls 16 of the housing by mushrooming projections 32 formed integrally with the side walls 16 of the housing over holes provided in the retaining clips 30.

The push button assembly 12 includes a hollow generally rectangular insulating member 34 which is formed with an open end over which is secured a light transmitting lens cap 36. The lens cap 36 is illuminated by electric lamps (not shown) mounted within the insulating member 34. An inner end or base 38 of the insulating member 34 engages a push rod 40 which passes through an aperture 41 formed in the base 22 of the housing 14. The insulating member 34 together 'with the push rod 40 forms an actuator to operate a device attached at the base 22 of the housing assembly 10 when an actuating force is applied to the lens cap 36. The rectangular insulating member 34 is biased outwardly by a coil spring 42, but is held within the receptacle 14 by a retaining device (not shown).

The novel and improved holding mechanism 44 which will be hereinafter further described, is formed with a housing 46 which is secured at one end to the housing 14 of the actuator housing assembly 10, and at the opposite end to a housing 48 of a switching device 50. As will be hereinafter described in further detail, the switching device 50 may be secured directly to the push button housing 14 in those applications where the holding mechanism 44 may be omitted. To this end, the push button housing 14 and the end of the holding mechanism housing 46 which is adapted to be attached to the switching device housing 48 'are provided with a rst type of attaching means, while the switching device housing 48 and the end of the holding mechanism housing 46 which is adapted to be attached to the push button housing 14 are provided with a second type of attaching means. The first and second types of attaching means are adapted to be attached to each other.

The housing -48 of the switching device 50 is comprised of two identical insulating housing members 52 and is substantially open at the top 54 and is substantially closed at the bottom 56. The bottom 56 supports terminals 58 which are connected to contacts (not shown) in the switching device and also a plate `60 which supports one end of a coil spring `62, the other end of which engages an operating member `64 which is movable between actuated and unactuated positions to actuate movable contacts (not shown) in the switching device so as to open and close the contacts of the switching device.

Referring to FIG. 3, it may be observed that in those applications where the holding mechanism 44 is omitted, the switch device 50 may be secured directly to the push button actuating device housing assembly 10. In such a case the lower end `66 of the push rod 40 would then engage upper edge 68 of operating member 64. When the switching device 50 is secured directly to the push button actuating device assembly 10 the operating member 64 must be modified to eliminate a pair of upwardly extending arms 69 which are provided to support movable contacts within the holding mechanism housing 46. When so assembled, both the operating member 64 and the push rod 40 are biased upwardly by the spring 62 to their unactuated positions.

In accordance with the invention an improved unitary holding mechanism is provided for electromagnetically holding the operating member -64 of the switch device 50 in its actuated position. The holding mechanism 44 comprises a housing 46 which fixedly supports therein a coil and a rst fixed portion of a magnetic assembly. The housing 46 also supports a second movable portion of the magnetic assembly which is positioned to transmit motion of push button assembly 12 to the operating member `64 in the switching device 50. The holding mechanism includes means effective when the movable portion of the magnetic assembly is moved to its actuated position to energize the coil to electromagnetically retain the movable portion in its actuated position so long as the coil is energized, the movable portion in turn holding the operating member `64 of the switching device 50 in its actuated position.

According to the specific embodiment illustrated, as is best seen in FIG. 2, the holding mechanism 44 includes a coil 70 which is wound on an insulating bobbin 72. An insulating material such as insulating tape covers the periphery of the coil and along with the bobbin substantially encloses the coil within an insulating means. The xed portion of the magnetic assembly is formed of three magnetic members comprising a cylindrical tubular magnetic member 74 surrounding the periphery of the coil 70 and two flat disk shaped magnetic members 76 and 78 inclosing the ends of the coil. Disk shaped magnetic member 76 is provided with a cylindrical projection 80 of the same diameter as the cylindrical bore of the coil bobbin 72 to be received therein. The projection 80 extends only a portion of the way within the bore in the bobbin. Notches 82 are provided in the periphery of the member 76 for receiving leads 84 and 86 of the coil. Disk shaped magnetic member 78 is formed 'with an aperture 8K8 therein which is of the same diameter as the bore in the bobbin 72. The movable portion of the magnetic assembly is formed as a part of a plunger assembly 90 having a first magnetic portion 92 of a larger diameter corresponding to that of the bore in the bobbin 72, and a second non-magnetic portion 94 of a smaller diameter.

In order to support the xed portion of the magnetic assembly the housing `46 is formed of two identical housing halves 96 and 98 each provided with tabs 100 for supporting disk shaped magnetic member 76, and with surfaces 102 spaced from and facing tabs 100 for engaging disk shaped magnetic member 78. The arrangement is such that upon assembling the housing halves 96 and 98 the xed portion of the magnetic assembly and therefore the coil 70 and bobbin 72 are detachably secured within the housing 46. To prevent rotation of the bobbin 72 and of disk shaped magnetic member 76, projections 104 are provided on the housing halves which extend into the notches 82 formed in the disk shaped magnetic member 76.

In order to provide means for making electrical connections to the coil 70, and to fixed contacts of the control switch which controls energization of the coil, a pair of grooves 106 are provided in the housing halves 96 and 98 for supporting L-shaped terminals 108, 110, 112, and 114. Leads 84 and 86 of coil 70 are electrically and mechanically connected, such as by soldering, to terminals 108 and 110 respectively. Terminals 112 and 114 are provided with fixed contacts 116 and 118 respectively which cooperate with movable contacts carried by operating member 64 to form the control switch.

As best seen in FIG. 2, in order to support the movable contacts of the control switch, operating member 64 is provided with a pair of upwardly extending arms 69 in which are formed notches 124. A contact supporting member 128 and a coil spring 130 are received in one of the notches 124 in arrangement whereby the contact support member 128 is resiliently supported by the operating member 64. Secured to the contact supporting member 128 are a pair of movable bridging contacts 132 and 134. As shown in FIGS. 3 and 4, movable bridging contact 132 is positioned to engage xed contact 116 supported yby terminal 112. Similarly, although not shown, movable bridging contact 134 is positioned to engage fixed contact 118.

Having thus described the principal elements of the holding mechanism 44, and having previously described the switching device 50 and the actuating device with which it is used, the method of assembling the holding mechanism 44 to the actuating device and the switching device 50 will be described. The iixed portion of the magnetic assembly comprising magnetic members 74, 76, and 78 is assembled about the coil 70 and bobbin 72, and the plunger assembly 90 is positioned in the apertures in the disks and in the bobbin bore. The terminals 108, 110, 112, and 114 are inserted in the grooves 106 in the housing halves 96 and 98, and the leads 84 and 86 are connected to the terminals 108 and 110.

With the magnetic assembly pisitioned in one of the housing halves, the housing halves are brought together around arms 69 of the operating member 64, with the fixed contacts 11-6 and 118 positioned under the movable contacts 132 and 134. When the housing halves 96 and 98 have been brought together, tabs 136 and 138 extending therefrom fit into notches, only one of which 140 is shown, formed by the identical housing members 52 of the switch housing 48. As seen in FIG. 1, tab 138 fits into notch 140.

In a similar manner, as the housing halves 96 and 98 of the holding mechanism housing 46 are brought together, notches 142 and 144 formed in the housing halves 96 and 98 respectively, engage tabs, only one of which 146 is shown, extending from the side walls 16 of the actuating device housing 14. Bars 148 and 150 extending across the notches 142 and 144 respectively are received in grooves, only one of which 152 is shown, formed in the tabs. With the three housings 14, 46, and 48 assembled, rivets 154 and 156 extending through apertures 158 and 1160 formed in the housing halves 96 and 98 secure the housing halves to each other and to the actuating device housing 14. Similarly, apertures are provided in the switching device insulating housing members 52 for receiving rivets 162 and 164 which secure the housing members together. Rivets 162 and 164 are also received in grooves 166 formed in tabs 136 and 138 so as to secure the holding mechanism housing 46 to the switching device housing 48.

Referring to the side of the composite assembly shown in FIG. l, the previoiusly mentioned rst type of attaching means is formed on the actuating device housing 14 by the tab 146 having the groove 152 formed therein, and on the holding mechanism housing 46 by the tab 138 having the groove 166 formed therein. The previously mentioned second type of attaching means is formed on the switch housing 48 by the notch 140 along with the rivet 164, and on the holding mechanism housing by notch 144 and bar 150 which extends across the notch. As previously set forth, in those applications where the holding mechanism 44 may be omitted, the rst type of attaching means formed on the actuating device housing 14 is secured to the second type of attaching means formed on the switch housing 48. That is, the tab 146 is placed in the notch 140 and the rivet 164 is then secured in the groove 152.

The operation of the holding device may now be understood by making reference to FIGS. 3-6. Depression of the push button assembly 12 by applying an actuating force thereto causes it to engage and depress push rod 40 which in turn engages top end 168 of plunger assembly 90 and depresses the plunger assembly 90 until its downward movement is stopped by engagement of the lower end 170 of its iirst magnetic portion 92 with the top surface 172 of the cylindrical projection 80 formed on disk shaped magnetic member 76 as shown by the dashed lines in FIG. 4.

Before the push button assembly 12 is depressed, the fixed contacts 11-6 and 118 are not engaged by the movable contacts 132 and 134 respectively, being biased to an open position by spring 62. Depression of the plunger assembly 90 causes its lower end 174 to engage the upper edge 68 of the operating member 64 so as to depress the operating member 64 and bring the movable bridging contacts 132 and 134 into engagement with the iixed 6. contacts 116 and 118, and also actuate the contacts of switching device 50. The closed position of the contacts is shown in FIG. 5.

The plunger assembly is electromagnetically maintained in its depressed position by the energization of coil 70 through the circuit shown in FIG. 6. Referring to FIG. 6, by a circuit external to the holding mechanism, terminals 108 and 112 are connected to each other, so as to connect fixed contact 116 to coil lead 84. Terminals and 114 are connected vby conductors 176 and 178 to a source of voltage (not shown). Thus, when movable bridging contacts 132 and 134 engage fixed contacts 11-6 and 118 upon depression of push button assembly 12, coil 70 is energized from the voltage source (not shown). Energization of the coil 70 creates a magnetic field which pass through the first fixed portion and the second movable portion of the magnetic assembly, to hold the second movable portion, and therefore plunger assembly 90 in its depressed position.

Upon removal of the actuating force from the push button assembly 12 it will be moved upward under the bias of coil spring 42, thereby removing the downward force applied to push rod 40. Spring 62 in the switching device 50 will attempt to move the operating member 64 and the plunger assembly 90 upward but, such movement of plunger assembly 90 would create an air gap between the lower end of rst magnetic portion 92 of the plunger assembly and the top surface 172 of the projection 80 on disk shaped magnetic member 76. The magnetic l'ield created by the energization of coil 70 resists the formation of this air gap and thus maintains the plunger assembly 90 and the operating member 64 in their depressed or actuated positions until the coil 70 is deenergized. The second portion 94 of the plunger assembly 90 is preferably formed as a non-magnetic shaft for the reason that a magnetic path through the shaft 94 would bridge the air gap to provide a ux path such that the magnetic -feld across the air gap might be so weakened that the plunger assembly 90 would not be maintained in its actuated position. It is readily observed that maintenance of operating member 64 in its actuated position also maintains the contacts in the switching device 50 in their actuated condition. The coil 70 may be deenergized by providing a suitable circuit interrupting element (not shown) in the circuit connected between terminals 108 and 112.

While particular embodiments of this invention have been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made without `departing from this invention in its broader aspects and, therefore, it is intended that the appended claims cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. A unitary electromagnetic holding mechanism comprising:

(a) a housing;

(b) a coil supported within said housing, said coil being formed with a central bore and being coniined within a pair of opposing sides and a peripheral surface;

l(c) a magnetic assemblyhoused within said housing and operatively associated with said coil to provide a magnetic path encircling said coil;

(d) said magnetic assembly including a xed magnetic portion, and a movable magnetic portion movable from an unactuated position to an actuated position;

(e) said fixed magnetic portion comprising a first magnetic member surrounding the peripheral surface of said coil, a second magnetic member-covering one end of said coil and having an aperture therein in alignment with siad bore, and a third magnetic member covering the other end of said coil;

(f) said movable magnetic portion comprising a fourth magnetic member received in both the bore of said coil and the aperture in said second magnetic member for reciprocal movement, whereby with said xed magnetic portion, said fourth magnetic member in said actuated position forms a magnetic path completely encircling said coil;

(g) an actuatable control switch supported within said housing, said actuatable control switch having at least one ,fixed contact and at least one movable contact movable between an open circuit position and a closed circuit position relative to said fixed contact;

(h) circuit means interconnecting said contacts of said actuatable control switch, said magnetic portions of said magnetic assembly, and said coil;

(i) actuating means operatively associated with said magnetic assembly and said actuatable control switch for moving said movable magnetic portion of said magnetic assembly to said actuated position and said movable contact of said actuatable control switch to said closed circuit position to energize said coil in response to the actuation of said actuating means by the application thereto of an external actuating force;

(j) the removal of said external actuating force from said actuating means causing said actuating means to return to its unactuated position, said coil in its energized state maintaining said movable magnetic portion in said actuated position and said movable contact in said closed circuit position following removal of said external actuating force; and

(k) said movable magnetic portion vof said magnetic assembly being returned to said unactuated position and said movable contact of said actuatable contact switch being returned to said open circuit position only by subsequent deenergization of said coil.

2. The unitary electromagnetic holding mechanism defined in claim 1 wherein said coil is substantially enclosed within an insulating means, said first magnetic member is a tube having an inside surface which substantially conforms to the peripheral surface of said coil, said second magnetic member is a plate, said aperture in said plate being in alignment with and substantially conforming to the shape of said bore in said coil, said third magnetic member is a plate having a projection extending from one of its faces which is received in the bore of said coil, said fourth magnetic member is of substantially the same cross-section as said projection and is spaced apart from said projection in the unactuated position and engages said projection in the actuated position to form said magnetic path completely encircling said coil.

3. The unitary electromagnetc holding mechanism defined in claim 2 wherein the bore in said coil, said aperture in said second magnetic member, said projection on said third magnetic member, and said fourth magnetic member are all of substantially cylindrical cross-section and are all of substantially the same diameter, said inside surface of said tube and the peripheral surface of said coil being substantially cylindrical and of substantially the same diameter, said second magnetic member and said third magnetic member being flat disks of substantially the same diameter as said tube, and said fourth magnetic member and a non-magnetic shaft form a plunger, with said shaft extending through an aperture which is formed in said third magnetic member passing through said projection.

4. The unitary electromagnetic holding mechanism dened in claim 1 wherein said housing is formed of two identical housing halves which are secured to each other with said coil and said fixed magnetic portion being secured therebetween.

5. The unitary electromagnetic holding mechanism defined in claim 1 wherein said housing supports a plurality of terminals which extend through the housing, and are internally connected by said circuit means to said coil and said control switch fixed contact, whereby connections may be made to said coil and said control switch externally of the housing.

6. In combination with an electric switching device including a switch housing enclosing at least one xed contact, at least one movable contact, and an operating member which is movable between an unactuated and an actuated position to actuate said movable contact, and an actuating device including an actuator housing enclosing an actuator movable from an unactuated to an actuated position by the application thereto of an actuating force, a unitary electromagnetic holding mechanism comprising:

(a) a holding mechanism housing adapted to be associated with said switch and actuator housings to form a composite housing;

(b) a coil supported within said holding mechanism housing, said coil being formed with a central bore and being confined within a pair of opposing sides and a peripheral surface;

(c) a magnetic assembly housed within said holding mechanism housing and operatively associated with said coil to provide a magnetic path encircling said coil;

(d) said magnetic assembly including a fixed magnetic portion, and a movable magnetic portion movable from an unactuated position an an actuated position;

(e) said fixed magnetic portion comprising a first magnetic member surrounding the peripheral surface of said coil, a second magnetic member covering one end of said coil and having an aperture therein in alignment with said bore, and a third magnetic member covering the other end of said coil;

(f) said movable magnetic portion comprising a fourth magnetic member received in both the bore of said coil and the aperture in said second magnetic member for reciprocal movement, whereby with said fixed magnetic portion, said fourth magnetic member in said actuated position forms a magnetic path completely encircling said coil;

(g) an actuatable control switch supported within said holding mechanism housing, said actuatable control switch having at least one fixed contact and at least one movable contact movable between an open circuit position and a closed circuit position relative to said fixed contact;

(h) circuit means interconnecting at least said contacts of said actuatable control switch, said magnetic portions of said magnetic assembly, and said coil;

(i) actuating means comprising said actuator enclosed in said actuator housing in operatively associated relation with said magnetic assembly and said actuable control switch for moving said movable magnetic portion of said magnetic assembly to said actuated position and said movable contact of said actuatable control switch to said closed circuit position to energize said coil in response to the actuation of said actuator by the application thereto of said actuating force, and for moving said operating member from said unactuated position thereof to said actuated position thereof to actuate said movable contact enclosed in said switch housing;

(j) the removal of said actuating force from said actuator causing said actuator to return to its unactuated position, said coil in its energized state maintaining said movable magnetic portion in said actuated position, said movable contact of said actuatable control switch in said closed circuit position, said operating member in said actuated position, and said movable Contact enclosed in said switch housing in said actuated position following removal of said actuating force; and

(k) said movable magnetic portion of said magnetic assembly being returned to said unactuated position, said movable contact of said actuatable contact switch being returned to said open circuit position, said operating member being returned to said unactu- 9 ated position, and said movable contact enclosed in said switch housing being returned to its unactuated position only by subsequent deenergization of said coil.

7. The combination defined in claim 6 wherein said coil is substantially enclosed within an insulating means, said iirst magnetic member is a tube having an inside surface which substantially conforms to the peripheral surface of said coil, said second magnetic member is a plate, said aperture in said plate being in alignment with and substantially conforming to the shape of said bore in said bore in said coil, said third magnetic member is a plate having a projection extending from one of its faces which is received in the bore of said coil, said fourth magnetic member is of substantially the same cross-section as said projection and is spaced apart from said projection in the unactuated position an engages said projection in the actuated position to form said magnetic path completely encircling said coil.

8. The combination defined in claim 7 wherein the bore in said coil, said aperture in said second magnetic member, said projection on said third magnetic member, and said fourth magnetic member are all of substantially cylindrical cross-section and are all of substantially the same diameter, said inside surface of said tube and the peripheral surface of said coil being substantially cylindrical and of substantially the same diameter, said second magnetic member and said third magnetic member being flat disks of substantially the same diameter as said tube, and said fourth magnetic member and a non-magnetic shaft form a plunger, with said shaft extending through an aperture which is formed in said third magnetic member passing through said projection.

9. In combination with an electric switching device including a switch housing enclosing at least one fixed contact, at least one movable contact, and an operating member which is movable between an unactuated and an actuated position to actuate said movable contact, and an actuating device including an actuator housing enclosing an actuator movable from an unactuated to an actuated position by the application thereto of an actuating force, a unitary electromagnetic holding mechanism comprising:

(a) an electromagnetic holding mechanism housing adapted to be associated with said switch and actuator housings to form a composite housing;

(b) said electromagnetic holding mechanism housing having one end attached to said switch housing and an opposite end attached to said actuator housing such that said holding mechanism is positioned between said switch housing and said actuator housing;

(c) a coil supported within said electromagnetic holding mechanism housing;

(d) a magnetic assembly housed within said electromagnetic holding mechanism housing and operatively associated with said coil to provide a magnetic path encircling said coil;

(e) said magnetic assembly including a fixed magnetic portion, and a movable magnetic portion movable from an unactuated position to an actuated position;

(f) said movable magnetic portion comprising a part of a plunger assembly having one end in engagement with said operating member and an opposite end in engagement with said actuator so as to operatively interconnect said switching device and said actuating device;

(g) an actuatable control switch supported within said electromagnetic holding mechanism housing, said actuatable control switch having at least one fixed contact and at least one movable contact movable between an open circuit position and a closed circuit position relative to said fixed contact;

(h) circuit means interconnecting at least said contacts of said actuatable control switch, said magnetic portions of said magnetic assembly, and said coil;

(i) actuating means comprising said actuator enclosed in said actuator housing in operatively associated relation with said magnetic assembly and said actuatable control switch for moving said movable magnetic portion of said magnetic assembly to said actuated position and said movable contact of said actuatable control switch to said closed circuit position to energize said coil in response to the actuation of said Aactuator by the application thereto of said actuating force, and for moving said operating member from said unactuated position thereof to said actuated position thereof to actuate said movable contact enclosed in said switch housing;

(j) the removal of said actuating force from said actuator causing said actuator to return to its unactuated position, said coil in its energized state maintaining said movable magnetic portion in its actuated position, said movable contact of said actuatable control switch in said closed circuit position, said operating member in said actuated position, and said movable contact enclosed in said switch housing in said actuated position following removal of said actuating force; and

(k) said movable magnetic portion of said magnetic assembly being returned to said unactuated position, said movable contact of said actuatable contact switch being returned to said open circuit position, said operating member being returned to said unactuated position, and said movable contact enclosed in said switch housing being returned to its unactuated position only by subsequent deenergization of said coil.

10. The combination defined in claim 9 wherein said electromagnetic holding mechanism housing has a first type of attaching means provided at said one end and a second type of attaching means provided at said opposite end, the switch housing being provided at one end with said second type of attaching means and the actuator housing being provided with said first type of attaching means, said first and second types of attaching means being adapted to be attached to each other, whereby the switch housing may be readily attached to the actuator housing or said holding mechanism housing may readily be attached between the switch housing and the actuator houslng.

11. In combination with an electric switching device including a switch housing enclosing at least one lixed contact, at least one movable contact, and an operating member which is movable between an unactuated and an actuated position to actuate said movable contact, and an actuating device including an actuator housing enclosing an actuator movable from an unactuated to an actuated position by the application thereto of an actuating force, a unitary electromagnetic holding mechanism comprising:

(a) an electromagnetic holding mechanism housing adapted to be associated with said switch and actuator housings to form a composite housing;

(b) a coil supported within said electromagnetic holding mechanism housing;

(c) a magnetic assembly housed within said electromagnetic holding mechanism housing and operatively associated with said coil to provide a magnetic path encircling said coil;

(d) said magnetic assembly including a fixed magnetic portion, and a movable magnetic portion movable from an unactuated position to an actuated position;

(e) said electromagnetic holding mechanism housing being formed of two identical housing halves which are secured to each other with said coil and said iixed magnetic portion being secured therebetween;

(f) an actuatable control switch supported within said electromagnetic holding mechanism housing, said actuatable control switch having at least one fixed contact and at least one movable contact between an open circuit position and a closed circuit position relative to said fixed contact;

(g) circuit means interconnecting at least said contacts of said actuatable control switch, said magnetic portions of said magnetic assembly, and said coil;

(h) actuating means comprising said actuator enclosed in said actuator housing in operatively associated relation with said magnetic assembly and said actuatable control switch for moving said movable magnetic portion of said magnetic assembly to said actuated position and said movable contact of said actuatable control switch to said closed circuit position to energize said coil in response to the actuation of said actuator by the application thereto of said actuating force, and for moving said operating member from said unactuated position thereof to said actuated position thereof to actuate said movable contact enclosed in said switch housing;

(i) the removal of said actuating force from said actuator causing said actuator to return to its unactuated position, said coil in its energized state maintaining said movable magnetic portion in said actuated position, said movable contact of said actuatable control switch in said closed circuit position, and said movable contact enclosed in said switch housing in said actuated position following removal of said actuating force; and

(j) said movable magnetic portion of said magnetic assembly being returned to said unactuated position, said movable contact of said actuatable contact switch being returned to said open circuit position, said operating member being returned to said unactuated position, and said movable contact enclosed in said switch housing being returned to its unactuated position only by subsequent deenergization of said coil.

12. In combination with an electric switching device including a switch housing enclosing at least one xed contact, at least one movable contact, and an operating member which is movable between an unactuated and an actuated position to actuate said movable contact, and an actuating device including an actuator housing enclosing an actuator movable from an unactuated to an actuated position by the application thereto of an actuating force, a unitary electromagnetic holding mechanism comprising:

(a) an electromagnetic holding mechanism housing adapted to -be associated with said switch and actuator housing to form a composite housing;

(b) a coil supported within said electromagnetic holding mechanism housing;

(c) a magnetic assembly housed within said electromagnetic holding mechanism housing and operatively associated with said coil to provide a magnetic path encircling said coil;

(d) said magnetic assembly including a iixed magnetic portion, and a movable magnetic portion movable from an unactuated position to an actuated position;

(e) an actuatable control switch supported within said electromagnetic holding mechanism housing said actuatable control switch having at least one fixed contact and at least one movable contact movable between an open circuit position and a closed circuit position relative to said fixed contact;

(f) said electromagnetic holding mechanism housing being formed to house therein said fixed contact and said movable contact of said control switch;

(g) circuit means interconnecting at least said contacts of said actuatable control switch, said magnetic portions of said magnetic assembly, and said coil;

(h) actuating means comprising said actuator enclosed in said actuator housing in operatively associated relation with said magnetic assembly and said actuatable control switch for moving said movable vmagnetic portion of said magnetic assembly to said actuated position and said movable contact of said actuatable control switch to said closed circu1t position to energize said coil in response to the actuation of said actuator by the application thereto of :said actuating force, and for moving said operating member from said unactuated position thereof to said actuated position thereof to actuate said movable contact enclosed in said switch housing;

(i) the removal of said actuating force from said actuator causing said actuator to return to its unactuated position, said coil in its energized state maintaining said movable magnetic portion in said actuated position, said movable contact of said actuatable control switch in said closed circuit position, said operating member in said actuated position, and said movable contact enclosed in said switch housing in said actuated position following removal of said actuating force; and

(j) said movable magnetic portion of said magnetic assembly being returned to said unactuated position, said movable contact of said actuatable contact switch being returned to said open circuit position, :said operating member being returned to said unactuated position, and said movable contact enclosed in said switch housing being returned to its position only by subsequent deenergization of said coil.

13. The combination defined in claim 12 wherein said movable contact of said control switch is supported by the operating member of the switching device within said electromagnetic holding mechanism housing.

14. The combination defined in claim 12 wherein said electromagnetic holding mechanism housing supports a plurality of terminals which extend through the housing, and are internally connected by said circuit means toy said coil and said control switch ixed contact, whereby connections may be made to said coil and said control switch externally of the housing.

15. A unitary electromagnetic holding mechanism comprising:

(a) a housing;

(b) a coil supported within said housing;

(c) a magnetic assembly housed within said housing and operatively associated with `said coil to provide a magnetic path encircling said coil;

(d) said magnetic assembly including a iixed magnetic portion, and a movable magnetic portion movable from an unactuated position to an actuated position;

(e) said movable magnetic portion comprising a plunger assembly;

(f) a control switch supported within said housing in operatively associated engagement with said plunger assembly;

(g) said control switch having at least one fixed contact and at least one movable contact movable between an open circuit position and a closed circuit position relative to said lixed contact in response to actuation of said control switch by said plunger assembly;

(h) circuit means interconnecting said contacts of said control switch, said magnetic portions of said magnetic assembly, and said coil;

(i) actuating means supported within said housing for movement relative thereto between an unactuated position and an actuated position;

(j) said actuating means comprising an actuator and a push rod, said push rod having one end in operatively associated enga-gement with said actuator and the other end in operatively associated engagement with said plunger assembly;

(k) said actuating means being movable to lsaid actuated position thereof upon the application of an external actuating force to said actuator, movement of said actuator in response to the application thereto of said external actuating force being transmitted to said push rod and from said push rod to said plunger assembly to move said movable contact of able contact of said control switch and thereby with said control switch to said closed circuit position to said plunger assembly; and

energize said coil; (o) :said second spring means upon deenergization of (l) rst spring means supported within said housing said coil causing said movable contact of said conin spring biasing relation to said actuator of said 5 trol switch to return to said open circuit position actuating means; and said plunger assembly of said movable magnetic (m) said rst spring means upon the removal of said portionof said magnetic assembly to said unactuated external actuating force from said actuator causing position thereof.

said actuator of said actuating means to return to said unactuated position thereof, said coil in its en- 10 References Cited ergized state maintaining said plunger assembly in UNITED STATES PATENTS said actuated position of said movable magnetic portion and said movable contact in said closed circuit position following removal of said external actuating force- 15 (n) second spring means supported within said hous- BERNARD A GFHEANY nmary Exammer ing in operatively associated relation with said mov- H. BROOME, Asslstant Examiner 2,611,843 9/1952 Bourne 335-107 3,153,124 10/1964 Bury 335--186 

